Susceptor for high temperature process

Abstract

To provide a susceptor structure that can suppress deterioration of the joint between a ceramic and a base during high-temperature processes, and a susceptor with a structure that allows individual temperature control for multiple heating zones while using AlN material with high thermal conductivity as a ceramic material.SOLUTION: An electrostatic chuck 100 as a susceptor includes a base member 120 having a first cooling gas flow path 122 for allowing a cooling gas to flow in, a heat insulating member 130 having a thermal conductivity of 20 W / mK or less and stacked on the base member, the heat insulating member 130 has a second cooling gas flow path 132 communicating with the first cooling gas flow path, and an insulating plate 110 stacked on the heat insulating member and having a plurality of gas holes 112 communicating with the second cooling gas flow path to eject a cooling gas for cooling the substrate.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a susceptor, and more particularly, to a susceptor for supporting a substrate in a high-temperature semiconductor process.

Background Art

[0002] Semiconductor elements and display elements are formed by laminating and patterning a plurality of thin film layers including a dielectric layer and a metal layer on a glass substrate, a flexible substrate, or a semiconductor wafer substrate by semiconductor processing such as a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process, an ion implantation process, and an etching process. A susceptor for supporting various substrates such as a glass substrate, a flexible substrate, and a semiconductor wafer substrate is used in a chamber for performing such a semiconductor process. As a representative example, an electrostatic chuck (ESC) that fixes the substrate using electrostatic force can be mentioned.

[0003] FIG. 1 is a diagram schematically showing an example of a conventional electrostatic chuck.

[0004] Referring to FIG. 1, the electrostatic chuck includes a base 20 and an insulating plate 10 on the base.

[0005] The insulating plate 10 may be usually formed of a ceramic material such as alumina. Electrodes 14 such as a DC electrode, a heater electrode, and / or an RF electrode may be embedded in the insulating plate 10.

[0006] In order to uniformly cool the substrate on the insulating plate 10, the base 20 and the insulating plate 10 adhered thereto are provided with a predetermined cooling structure. The cooling gas flowing in through the cooling gas flow path 22 provided in the base 20 communicates with the gas holes 12 of the insulating plate 10 to cool the substrate. In such a conventional electrostatic chuck structure, the base 20 and the insulating plate 10 are adhered by an adhesive layer 30.

[0007] In the manufacturing process of semiconductor devices to which such an electrostatic chuck is applied, fine patterns are stacked in an ultra-high stage, and the aspect ratio of the device gradually increases in a direction where it continues to increase.

[0008] In the semiconductor process, the fabrication of high aspect ratio patterns leads to an increase in plasma voltage and process time. Especially for NAND processes with 200 or more levels, the application of a hard mask with excellent durability is essential. As a result, materials with excellent plasma resistance, such as boron-doped amorphous carbon layer and silicon oxynitride, are adopted as the material for the next-generation hard mask. Therefore, the difficulty of the etching process for etching the hard mask layer is increasing.

[0009] In order to improve the reactivity and selectivity required for the etching process for etching the hard mask layer, the electrostatic chuck must operate at a high temperature of 300 °C or higher. However, in a conventional electrostatic chuck, an organic material such as silicone is used as an adhesive between the ceramic and the metal body, so there is a problem that it deteriorates and decomposes at high temperatures and cannot maintain the adhesive force at the process temperature.

[0010] Moreover, a conventional electrostatic chuck has a high linear thermal expansion coefficient between the ceramic and the metal base. For this reason, a very large stress is generated in the adhesive layer between the base and the plate in a high-temperature process.

[0011] On one hand, in order to raise the temperature of the electrostatic chuck to be suitable for high-temperature processes, it is preferable to use a material having a high thermal conductivity such as AlN. However, since AlN has a very high thermal conductivity of 180 kW / m·K, there has been a problem that it is impossible to divide the heating region in the electrostatic chuck to control the temperature. Summary of the Invention Problems to be Solved by the Invention

[0012] In order to solve the above problems of the prior art, an object of the present invention is to provide a susceptor structure capable of suppressing deterioration of the joint portion between the insulating plate and the base in a high-temperature process.

[0013] Another object of the present invention is to provide a susceptor based on a non-adhesive structure between an insulating plate and a base so as to be suitable for application in a high-temperature process.

[0014] Another object of the present invention is to provide a susceptor having a structure capable of individually controlling the temperature for a plurality of heating zones while using an AlN material with high thermal conductivity as a ceramic material. Means for Solving the Problems

[0015] To achieve the above technical problems, the present invention provides a susceptor including a base member having a first cooling gas flow path for flowing in a cooling gas, a heat insulating member having a second cooling gas flow path communicating with the first cooling gas flow path and having a thermal conductivity of 20 W / mK or less laminated on the base member, and an insulating plate laminated on the heat insulating member and having a plurality of gas holes for ejecting a cooling gas for cooling a substrate by communicating with the second cooling gas flow path.

[0016] In the present invention, the heat insulating member may be made of quartz material or may include any one material selected from the group consisting of Kovar, Ti, and Hastelloy.

[0017] In the present invention, the heat insulating member may be a rigid plate.

[0018] Also, in the present invention, the base member may be a metal matrix composite (MMC) or aluminum.

[0019] In the present invention, it is preferable that the heat conductivity of the insulating plate at 300 °C is 50 W / mK or less. In this case, the insulating plate may be made of aluminum nitride and may further contain Mg and Ti. At this time, the Mg content in the aluminum nitride material is preferably 1 to 3 wt% in terms of MgO, and the Ti content is preferably 0.1 to 0.5 wt% in terms of TiO2.

[0020] In the present invention, it is preferable that the heat conductivity of the heat insulating member at 300 °C is 20 W / mK or less.

[0021] In the present invention, it is preferable that the coefficient of thermal expansion of the heat insulating member at 300 °C is 10 μm / mK or less.

[0022] In the present invention, the first surface of the heat insulating member in contact with the base member and the second surface of the heat insulating member in contact with the insulating plate may each include an outer ring disposed along the outer contour of the laminated structure.

[0023] Also, the present invention includes a plurality of fastening devices that penetrate and join the laminated structure vertically at the outer contour of the laminated structure, and the outer ring may be disposed inside the plurality of fastening devices.

[0024] In the present invention, the susceptor includes gas holes in the insulating plate for cooling the substrate on the insulating plate, and the gas holes may communicate with the cooling gas communication holes of the base member.

[0025] In the present invention, the heat insulating member includes a first surface in contact with the base member and a second surface in contact with the insulating plate, and an O-ring for sealing the second cooling gas flow path can be provided on each of the first surface and the second surface of the heat insulating member.

Advantages of the Invention

[0026] According to the present invention, it becomes possible to provide a susceptor structure capable of suppressing deterioration of the joint portion between the ceramic and the base in a high-temperature process. Further, according to the present invention, it becomes possible to provide a susceptor having a structure capable of individually controlling the temperature for a plurality of heating zones while using an AlN material having high thermal conductivity as the ceramic material.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the technical field.

[0029] Throughout this specification, when a part includes a certain component, unless otherwise specified, this means that other components may be further included rather than excluding other components. Also, in this specification, the expression "material A" is used to mean not only what consists only of substance A, but also what has substance A as the main component (a component of 50% by weight or more), but in which other substances other than substance A are mixed, or a composite substance of substance A and other substances. Further, in the present invention, "lamination" can refer to a state where two adjacent layers are in direct contact or a state where they are not in contact with each other through another layer.

[0030] FIG. 2 is a cross-sectional view for explaining the structure of the electrostatic chuck 100 according to an embodiment of the present invention.

[0031] Referring to FIG. 2, a susceptor according to an embodiment of the present invention includes a laminated structure of an insulating plate 110, a heat insulating member 130, and a base member 120.

[0032] In the present invention, the insulating plate 110 preferably has a circular shape, but may be designed in other shapes such as an elliptical shape or a rectangular shape in some cases.

[0033] In the present invention, the insulating plate 110 includes one or more electrode layers inside. By way of example, the electrode layer may include a chuck electrode layer 114A, a heater electrode layer 114B, and an RF electrode layer 114C, but it goes without saying that only a part of these electrode layers may be included. Also, although each electrode layer is shown as being formed of one layer, each electrode layer may be formed of two or more layers, or two or more electrode functions may be integrated into one electrode layer, which goes without saying. Further, an RF voltage may be applied to the base instead of the RF electrode layer 114C.

[0034] In the present invention, the insulating plate 110 may contain at least one substance selected from the group consisting of dielectric substances such as alumina (Al2O3), aluminum nitride (AlN), silicon carbide (SiC), silicon nitride (Si3N4), silicon oxide (SiO2), barium oxide (BaO), zinc oxide (ZnO), cobalt oxide (CoO), tin oxide (SnO2), zirconium oxide (ZrO2), yttria (Y2O3), and yttrium aluminates such as YAG, YAM, and YAP.

[0035] Preferably, in the present invention, the insulating plate 110 may be made of an AlN material. Since an insulating plate made of an AlN material generally exhibits a very high thermal conductivity, it is difficult to apply when the substrate is divided into a plurality of heating regions and independent temperature control is required. The present invention can use AlN with low thermal conductivity as the material of the insulating plate 110.

[0036] In the present invention, an AlN plate with low thermal conductivity can be achieved by controlling the addition amount of a sintering aid. Oxygen dissolved in the AlN lattice decreases the thermal conductivity of AlN. Therefore, by suppressing the content of alkaline earth metals such as Ca and Mg, rare earth metals such as yttrium (Y), and transition metals such as Ti, which are known as sintering aids, phonon scattering elements such as oxygen and vacancies can be retained in the lattice, and an AlN sintered body with low thermal conductivity can be manufactured. For example, the shaft may be an AlN sintered body containing 2 wt% or less of yttria as a sintering aid, and the thermal conductivity may be controlled by the content of the sintering aid such as yttria.

[0037] More preferably, the AlN plate of the present invention may contain Mg and Ti as metal elements. By adding MgO as a sintering aid, the thermal conductivity of the AlN plate may decrease. This may be due to the low thermal conductivity of the grain boundary phase such as spinel precipitated by the addition of MgO. In addition, since TiO2 added as a sintering aid binds to aluminum vacancies inside the AlN lattice, the aluminum vacancies can be retained within the AlN lattice. As a result, the thermal conductivity of AlN may decrease. The addition of MgO and TiO2 as sintering aids needs to be added above the minimum limit showing an effective effect, and since a saturation state may be reached as the addition amount increases, an appropriate amount needs to be added. Further, in the present invention, the content of Mg in the plate sintered body may be included at 0.1 wt% or more, 0.5 wt% or more, or 1.0 wt% or more on the basis of MgO conversion, and may be included at 3.0 wt% or less, 2.5 wt% or less, 2.4 wt% or less, 2.3 wt% or less, 2.2 wt% or less, 2.1 wt% or less, or 2.0 wt% or less. Further, the Ti content in the sintered body of the plate 110 may be included at 0.05 wt% or more, 0.1 wt% or more, 0.15 wt% or more, or 0.2 wt% or more on the basis of TiO2. Further, the Ti content in the sintered body may be included at 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, or 0.25 wt% or less.

[0038] In the present invention, the plate 110 made of the above-described AlN material may have a thermal conductivity of 80 W / mK or less, 70 W / mK or less, 60 W / mK or less, or 50 W / mK or less at a temperature of 300°C. For example, it is preferable that the AlN plate has a thermal conductivity of 40 to 60 W / mK at a temperature of 300°C.

[0039] In the present invention, the heater electrode layer 114B may be a multi-zone heater divided into a plurality of regions. For example, the heater electrode layer 114B may be a two-zone heater including two concentric heaters such as an internal heater layer and an external heater layer, or may be a multi-heater composed of a plurality of concentric heater layers. Alternatively, the heater electrode layer 114B may include a fan-shaped multi-heater radially divided into a plurality of heating zones.

[0040] By applying a plate made of AlN material with a relatively low thermal conductivity, the present invention enables the realization of a heater that exhibits different temperatures for different partitioned regions even when the multi-heater is applied as described above.

[0041] As described above, the insulating plate 110 has been described as forming a single body. However, it goes without saying that the insulating plate 110 may have a laminated structure composed of two or more insulating layers (dielectric layers).

[0042] In the present invention, the electrode layers 114A, 114B, and 114C may be made of a conductive metal material and may be connected to the connectors 140A, 140B, and 140C, respectively, to be supplied with power from the outside. As an example, the electrode layers 114A, 114B, and 114C may be formed of at least one of silver (Ag), gold (Au), nickel (Ni), tungsten (W), molybdenum (Mo), and titanium (Ti), and may be formed of tungsten (W), for example. In the present invention, the electrode layers 114A, 114B, and 114C may be formed by a screen printing process or may be realized by a metal workpiece such as a foil, a coil, or a mesh.

[0043] In the present invention, the base member 120 may be a multi-layer structure composed of a plurality of metal layers. These metal layers may be joined by a brazing process, a welding process, a bonding process, or the like.

[0044] In the present invention, the base member 120 may be made of a material such as aluminum, an aluminum alloy, or a metal matrix composite (MMC). The MMC may be, for example, a composite of Al and SiC, and a material with 20 to 70 wt% of SiC added may be used. When using MMC as the base member as in the present invention, the difference in the coefficient of thermal expansion between the base member and the heat insulating member can be reduced. Thereby, thermal deformation associated with the process can be minimized.

[0045] In the present invention, a ceramic coating layer 126 may be added to the surface of the base member 120 in order to improve the heat insulating property and reduce the thermal conductivity. For example, Al2O3, Y2O3, or a compound thereof may be formed on the surface of the base material by atmospheric plasma spraying coating.

[0046] A heat insulating member 130 is interposed between the insulating plate 110 and the base member 120.

[0047] The heat insulating member 130 suppresses heat exchange between the insulating plate 110 and the base 120. Preferably, the heat insulating member is preferably embodied with a material having a low thermal conductivity and a low coefficient of thermal expansion. In the present invention, the heat insulating member 130 may be a solid rigid plate. In the present invention, the heat insulating member 130 may preferably have a thickness of 5 to 20 mm.

[0048] In the present invention, the heat insulating member 130 preferably has a thermal conductivity of 20 W / mK or less, 15 W / mK or less, 10 W / mK or less, or 5 W / mK or less. Also, the heat insulating member preferably has a coefficient of thermal expansion of 15 μm / mK or less, 10 μm / mK or less, or 5 μm / mK or less.

[0049] For example, the heat insulating member is preferably embodied by one material selected from the group consisting of Kovar, Titanium, Hastelloy, and Quartz. Preferably, the heat insulating member may be embodied by Quartz.

[0050] The physical properties of the heat insulating member described above are shown in Table 1 below.

[0051]

Table 1

[0052] In the present invention, the susceptor includes a cooling mechanism by the inflow of a cooling gas such as He for cooling the substrate. The cooling mechanism may be embodied by a cooling gas flow path that communicates the plate, the heat insulating member, and the base member.

[0053] In the present invention, the base member 120 includes a first cooling gas flow path 122 for the inflow of a cooling gas from the outside. The first cooling gas flow path 122 communicates with the gas hole 112 of the insulating plate through the second cooling gas flow path 132 of the heat insulating member laminated on the base member 120, and the cooling gas is jetted toward the substrate side.

[0054] In the present invention, the susceptor includes a pair of O-rings 132A at both ends of the second cooling gas flow path 132 on the upper and lower surfaces of the heat insulating member in order to seal the flow of the cooling gas passing through the cooling gas flow path. In the present invention, the O-ring 132A may be embodied by a material having heat resistance at a high temperature of 300 °C or higher. For example, an O-ring made of a perfluorinated material having a high fluorine content such as FFKM with high thermal resistance may be used. Thereby, it becomes possible to stably maintain airtightness even in a high temperature process of 300 °C or higher.

[0055] In the present invention, a laminated structure including a base member 120, a heat insulating member 130, and an insulating plate 110 is coupled by a fastening device 150. The fastening device 150 may be based on a normal screw coupling structure such as a bolt that vertically penetrates the base member 120, the heat insulating member 130, and the insulating plate 110, and a nut coupled to the bolt.

[0056] The susceptor of the present invention includes an outer ring 132B for supporting a laminated structure of a base member, a heat insulating member, and a plate. The outer ring 132B may follow the contour shape of the insulating plate. For example, the ring may be a circular ring. As described above, it is preferable that the outer ring is also made of a material having heat resistance at a high temperature of 300 °C or higher, such as an FFKM ring.

[0057] As described above, the present invention has been described using exemplary embodiments and drawings. However, this is provided only to assist a more general understanding of the present invention, and the present invention is not limited to the above embodiments. It will be understood that those having ordinary knowledge in the field to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the idea of the present invention should not be defined only by the described embodiments, and it should be interpreted that not only the scope of the claims but also any technical idea equivalent or equivalent to the scope of the claims is included in the scope of the present invention.

Explanation of Reference Numerals

[0058] 110 Insulating plate 114A, 114B, 114C Electrode layer 120 Base member 122 First cooling gas flow path 24, 124 Refrigerant flow path 130 Heat insulating member 132 Second cooling gas flow path 132A Ring 132B Outer ring 140A, 140B, 140C Connector 150 Fastening device

Claims

1. A base member having a first cooling gas flow path for introducing a cooling gas; A heat insulating member having a heat conductivity of 20 W / mK or less laminated on the base member and having a second cooling gas flow path communicating with the first cooling gas flow path; An insulating plate laminated on the heat insulating member and having a plurality of gas holes for ejecting a cooling gas for cooling a substrate in communication with the second cooling gas flow path, the susceptor comprising:

2. The susceptor according to claim 1, wherein the heat insulating member is made of quartz.

3. The susceptor according to claim 1, wherein the heat insulating member contains a material selected from the group consisting of Kovar, Ti, and Hastelloy.

4. The susceptor according to claim 1, wherein the heat insulating member is a rigid plate.

5. The susceptor according to claim 1, wherein the base member is a metal matrix composite (MMC) or aluminum.

6. The susceptor according to claim 1, wherein the insulating plate has a heat conductivity of 50 W / mK or less at 300°C.

7. The susceptor according to claim 6, wherein the insulating plate is made of aluminum nitride.

8. The aluminum nitride material further contains Mg and Ti. The Mg content in the aluminum nitride material is 1 to 3 wt% in terms of MgO, and the Ti content is 0.1 to 0.5 wt% in terms of TiO ２ The susceptor according to claim 7, characterized in that it is as described above.

9. The susceptor according to claim 1, wherein the heat insulating member has a heat conductivity of 20 W / mK or less at 300°C.

10. The susceptor according to claim 1, wherein the heat insulating member has a coefficient of thermal expansion of 10 µm / mK or less at 300°C.

11. The susceptor according to claim 1, wherein the first surface of the heat insulating member in contact with the base member and the second surface of the heat insulating member in contact with the insulating plate each include an outer ring disposed along the outer contour of the laminated structure.

12. A plurality of fastening devices for vertically penetrating and joining the laminated structure at the outer contour of the laminated structure; The susceptor according to claim 11, wherein the outer ring is disposed inside the plurality of fastening devices.

13. The heat insulating member includes a first surface in contact with the base member and a second surface in contact with the insulating plate. The susceptor according to claim 1, characterized in that each of the first surface and the second surface of the heat insulating member is provided with an O-ring for sealing the second cooling gas flow path.

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